Perl Weekly Challenge 030

ch-1.pl

use strict;
use warnings;
##
# Write a script to list dates for Sunday Christmas between 2019 and 2100.
## 
sub day_of_week{
    my($year, $month, $day) = @_;
    my @month_value = (0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4); 
    $year-- if($month == 1 || $month == 2);  
    return ($year + int($year/4) - int($year/100) + int($year/400) + $month_value[$month-1] + $day) % 7
}

MAIN:{ 
    for my $year (2019 .. 2100){
        my $dow = day_of_week($year, 12, 25);
        print "$year\n" if $dow == 0; 
    }
}   

ch-2.pl

use strict;
use warnings;
##
# Write a script to print all possible series 
# of 3 positive numbers, where in each series 
# at least one of the number is even and sum 
# of the three numbers is always 12.
##
use boolean; 
use Math::Combinatorics;

sub has_even{
    my @numbers = @_;
    my @evens = grep { $_ % 2 == 0 } @numbers;
    if(@evens){
        return true; 
    }  
    return false; 
}

sub sums_12{
    my @numbers = @_;
    my $sum = unpack("%32I*", pack("I*", @numbers));  
    if($sum == 12){
        return true;
    }
    return false; 
}

MAIN:{
    my $combinations = new Math::Combinatorics(count => 3,
                                               data  => [-10 .. 10]  
    );
    my @combination = $combinations->next_combination();
    do{
        if(has_even(@combination) and sums_12(@combination)){
            print "@combination\n"; 
        } 
        @combination = $combinations->next_combination();
    } while(@combination);
}